1. Field of the Invention
The invention relates in general to a projector, and more particularly to a projector capable of adjusting brightness and brightness uniformity.
2. Description of the Related Art
Whether an optical path in a projector is well designed may influence the image representation of the projector, which is finally projected onto a screen. Thus, how to enhance the imaging brightness and uniformity of the projector effectively has become the focus, which is getting more and more concerned in the projector market.
FIG. 1 (Prior Art) is a schematic illustration showing a conventional projector 10. Referring to FIG. 1, the conventional projector 10 includes a light module 110, a light pipe 120, a first lens module 130, a second lens module 140, an image module 150 and a lens 160. The light module 110 includes a light bulb 112 and a bulb shade 114 for reflecting and converging the light ray L generated by the light bulb 112. The light pipe 120 includes an entrance 122 and an exit 124. The light ray L is converted into a light converging spot P on the entrance 122 and then homogenized by the light pipe 120 and outputted through the exit 124. The light ray L outputted through the exit 124 passes through the first lens module 130 and the second lens module 140, and is then inputted to the image module 150. The light ray L reflected by the image module 150 generates different brightness values and is then projected onto a screen 170 through the lens 160.
In order to make the image representation of the conventional projector 10 reach the predetermined target, the position of the light module 110 relative to that of the light pipe 120 is considered when the conventional projector 10 is being designed. Thus, it is possible to control the light converging spot P to fall on the optical axis A of the light pipe 120, and the better imaging brightness and uniformity may be obtained.
However, when the light module 110 is being manufactured, each component is not properly and precisely assembled. For example, the deviation in assembling the light bulb 112 and the bulb shade 114 together tends to shift the position of the light bulb 112 and thus the position of the light converging spot P. When the light converging spot P is shifted from the optical axis A of the light pipe 120, the imaging brightness and uniformity of the conventional projector 10 deteriorate.